1. Field of the Invention
This invention relates to environmental control systems and more particularly to an environmental control system controlling for an environment having a plurality of zones with a plurality of heating, ventilating and air conditioning units
2. Description of the Related Art
Various types of controllers and control systems have been known to the prior art for controlling an air processing units such as an air conditioning and/or heating unit. The most simple of these units comprise a single thermostat control couple to a single air conditioning and/or heating unit. Many complicated units comprise a computer having a plurality of thermostat sensors for controlling temperatures within a plurality of zones with a plurality of heating, ventilating and air conditioning units. Typically, a master control receives information from the plurality of thermostat sensors for controlling the plurality of heating, ventilating and air conditioning units. In some instances, the master control was provided with a program for reducing the peak demand of electrical power required by the plurality of heating, ventilating and air conditioning units.
In many regions of the country, providers of electrical service calculate the cost of electrical service based in part on the peak amount of electric power used by a customer on a given day. The peak amount of electricity used by a customer on a given day is commonly referred to as peak demand. By reducing the peak demand, the electrical customer substantially reduces the overall cost of electrical service.
Many in the prior art have incorporated a system for reducing the peak demand for an air conditioning and/or heating system in order to reduce the overall cost of operation. The following United States patents represents some of the efforts of the prior art for reducing the peak demand in an air conditioning and/or heating system.
U.S. Pat. No. 4,549,274 to Lerner et al discloses a distributed load processing system for shedding and/or adding loads controlled by a plurality of processors for maintaining power demand by the loads below a predetermined amount. The distributed load processing system includes a common communication channel and a plurality of processors connected to the common communication channel, a demand meter for sensing the power consumption per sample period so that the power consumption per sample period can be transmitted to all of the processors. Each processor compares the demand limit established for the system to the projected power per interval being consumed and for shedding and/or adding its associated loads based upon this comparison to maintain power consumption per interval below the demand limit.
U.S. Pat. No. 4,686,630 to Marsland et al discloses a load management control system and method which communicates load shedding information from a central station controller via existing telephone lines to a substation controller. The substation controller in turn controls the tap position selection of a load tap changing transformer to send encoded step voltage signals down a power distribution line to a load control receiver. The load control receiver decodes the encoded signal message and appropriately controls uniquely associated loads. The substation controller interrupts automatic operation of the voltage maintenance circuitry of the load tap changing transformer during transmission of a message. Control is returned to the automatic circuitry of the load tap changing transformer after the message is completed so as to make existence of the load management control system of the present invention transparent to existing equipment in the field. The method of the present invention maximizes utilization of existing lines of communication and existing power distribution field equipment while minimizing the effect on that same equipment.
U.S. Pat. No. 4,694,192 to Payne et al discloses a demand limit control system for maintaining power consumption of loads within a building below an upper demand limit. The upper demand limit is separated from a lower demand limit by a deadband. The system has a power demand controller responsive to power consumption for providing a controller output signal ramping up when the power consumption is above the upper demand limit. The controller output signal remains substantially constant when power consumption is between the upper and lower demand limits. The controller output signal ramps down when the power consumption is below the lower demand limit. A plurality of demand controlled loads are connected to the power demand controller and respond to a different threshold value of the controller output signal such that each load is conditioned to turn off when the controller output signal is above the threshold and is conditioned to turn on when the controller output signal is below the threshold.
U.S. Pat. No. 4,916,328 to Culp discloses an add/shed system and method for adding and shedding loads to maintain the power consumption of a building below the predetermined level. The system includes a plurality of loads and measures the present total power consumption of the building. Selected ones of the loads are reactively shed in response to the measured total power consumption of the building to maintain the present power consumption of the building below the predetermined level. The anticipated future increase or decrease in power consumption of the building is determined and selected ones of the loads are added or shed in response to the measured total power consumption of the building and the anticipated future increase or decrease in power consumption of the building for continuously maintaining the power consumption of the building below the predetermined level.
U.S. Pat. No. 5,103,391 to Barrett discloses a highly distributed direct digital process control system for use in controlling a fully distributed process including at least one device controller independently monitoring and controlling a plurality of external devices for performing a complete process. One or more data concentrator units are connected to the controllers for collecting information from each controller as well as directing updated control information to specific controllers. A central information processing means is connected to the data concentrator for displaying information received from the data concentrator. The central information processing means is capable of updating control information used by specific controllers.
U.S. Pat. No. 5,436,510 to Gilbert discloses a method for managing electric power in a network to which are connected, on the one hand, appliances capable of 2-way communication with each other, each appliance consisting of a power subassembly and a control subassembly and, on the other hand, a so-called power manager unit designed to manage load shedding and re connection functions exclusively affecting the said power subassemblies of each appliance with each disconnectable appliance being disconnected a priori. Any request for significant electric power made by a disconnected appliance results in a transaction between the said appliance and the power manager during which the said requesting disconnected appliances supplies the said power manager with information of a quantitative and qualitative nature concerning the power requested and on completion of which the said power manager authorizes or does not authorize re connection of the power subassembly of the said requesting appliance. The system is used for the implementation of home networks equipped with dynamic management of electric power.
U.S. Pat. No. 6,115,713 to Pascucci et al discloses a networked system having a wide variety of applications and particularly applicable to facilities management systems having multiple levels of software in processing nodes. The levels include a “features” processing level which communicates requests for data to a software object level containing databases of processes and attributes and database managers. The database managers in the software object level operate to provide data to the high level features in the same format. The software object level communicates with a hardware object level which also contains databases and database managers to mask differences between operational hardware units. By categorizing operational units by type, additional units of a known type can be added with only low level hardware object database changes. Adding units of a new type is facilitated by software changes confined to the lower level hardware and software objects, avoiding software changes at high level features. Individual software objects are tailored for typical types of inputs and output devices encountered by facilities management systems. Universal drive circuitry also provides applicability to a broad range of devices.
Therefore, it is an object of the present invention to provide an improved environmental control system for controlling the environment within a plurality of zones within a building with a plurality of heating, ventilating and air conditioning units.
Another object of this invention is to provide an improved environmental control system which alters the operation of a heating, ventilating and air conditioning unit in accordance with the operation of the remaining plurality of heating, ventilating and air conditioning units.
Another object of this invention is to provide an improved environmental control system that reduces the peak demand in electrical power required by all of the plurality of heating, ventilating and air conditioning units.
Another object of this invention is to provide an improved environmental control system that enables a staggered start function of the plurality of heating, ventilating and air conditioning units.
Another object of this invention is to provide an improved environmental control system that extends the period of time required for the heating, ventilating and air conditioning units to obtain the selected temperature.
Another object of this invention is to provide an improved environmental control system extends prevents the starting of a second heating, ventilating and air conditioning unit until a first heating, ventilating and air conditioning unit is finished normal operation.
Another object of this invention is to provide an improved environmental control system that alters the operation of a heating, ventilating and air conditioning unit in accordance the operational history of a selected one of the plurality of heating, ventilating and air conditioning units or in accordance with the operation of all of the plurality of heating, ventilating and air conditioning units.
Another object of this invention is to provide an improved environmental control system that provides multiple modes of operation including a preferred first non-overlap mode for preventing the simultaneous actuation of multiple heating, ventilating and air conditioning units.
Another object of this invention is to provide an improved environmental control system that provides a less preferred second overlap mode permitting simultaneous actuation of multiple heating, ventilating and air conditioning units for only a limited time period.
Another object of this invention is to provide an improved environmental control system that provides a least preferred third demand saver setback mode lessening the environment requirements to reduce the need to simultaneous actuate multiple heating, ventilating and air conditioning units.
Another object of this invention is to provide an improved environmental control system that disregards the operation of one of said plurality of heating, ventilating and air conditioning units operating in excess of a pre-selected period of time.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by modifying the invention within the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment of the invention.